C program to insert a node in doubly linked list
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This C program implements functions to create and manipulate a doubly linked list. It allows the user to choose from a menu to create a list, insert nodes at the beginning, end, or a specified position, and display the list. Functions are defined to create a list by dynamically allocating nodes and linking them together, insert nodes at different positions by updating next and prev pointers, and display the list by traversing from head to tail.
C program to insert a node in doubly linked list
- 1. ** * C program to insert a node in Doubly linked list */ #include <stdio.h> #include <stdlib.h> /* * Basic structure of Node */ struct node { int data; struct node * prev; struct node * next; }*head, *last; /* * Function used in this program */ void createList(int n); void displayList(); void insertAtBeginning(int data); void insertAtEnd(int data); void insertAtN(int data, int position); int main() { int n, data, choice=1; head = NULL; last = NULL; /* * Run forever until user chooses 0 */ while(choice != 0) { /* * Menu creation to use the program */ printf("============================================n"); printf("DOUBLY LINKED LIST PROGRAMn"); printf("============================================n"); printf("1. Create Listn"); printf("2. Insert node - at beginningn"); printf("3. Insert node - at endn"); printf("4. Insert node - at Nn"); printf("5. Display listn"); printf("0. Exitn"); printf("--------------------------------------------n"); printf("Enter your choice : "); scanf("%d", &choice); /*
- 2. * Choose from different menu operation */ switch(choice) { case 1: printf("Enter the total number of nodes in list: "); scanf("%d", &n); createList(n); break; case 2: printf("Enter data of first node : "); scanf("%d", &data); insertAtBeginning(data); break; case 3: printf("Enter data of last node : "); scanf("%d", &data); insertAtEnd(data); break; case 4: printf("Enter the position where you want to insert new node: "); scanf("%d", &n); printf("Enter data of %d node : ", n); scanf("%d", &data); insertAtN(data, n); break; case 5: displayList(); break; case 0: break; default: printf("Error! Invalid choice. Please choose between 0-5"); } printf("nnnnn"); } return 0; } /** * Creates a doubly linked list of n nodes. * @n Number of nodes to be created */ void createList(int n) { int i, data; struct node *newNode; if(n >= 1) { /*
- 3. * Create and link the head node */ head = (struct node *)malloc(sizeof(struct node)); printf("Enter data of 1 node: "); scanf("%d", &data); head->data = data; head->prev = NULL; head->next = NULL; last = head; /* * Create and link rest of the n-1 nodes */ for(i=2; i<=n; i++) { newNode = (struct node *)malloc(sizeof(struct node)); printf("Enter data of %d node: ", i); scanf("%d", &data); newNode->data = data; newNode->prev = last; // Link new node with the previous node newNode->next = NULL; last->next = newNode; // Link previous node with the new node last = newNode; // Make new node as last/previous node } printf("nDOUBLY LINKED LIST CREATED SUCCESSFULLYn"); } } /** * Display content of the list from beginning to end */ void displayList() { struct node * temp; int n = 1; if(head == NULL) { printf("List is empty.n"); } else { temp = head; printf("DATA IN THE LIST:n"); while(temp != NULL) { printf("DATA of %d node = %dn", n, temp->data); n++;
- 4. /* Move the current pointer to next node */ temp = temp->next; } } } /** * Inserts a new node at the beginning of the doubly linked list * @data Data of the first node i.e. data of the new node */ void insertAtBeginning(int data) { struct node * newNode; if(head == NULL) { printf("Error, List is Empty!n"); } else { newNode = (struct node *)malloc(sizeof(struct node)); newNode->data = data; newNode->next = head; // Point to next node which is currently head newNode->prev = NULL; // Previous node of first node is NULL /* Link previous address field of head with newnode */ head->prev = newNode; /* Make the new node as head node */ head = newNode; printf("NODE INSERTED SUCCESSFULLY AT THE BEGINNING OF THE LISTn"); } } /** * Inserts a new node at the end of the doubly linked list * @data Data of the last node i.e data of the new node */ void insertAtEnd(int data) { struct node * newNode; if(last == NULL) { printf("Error, List is empty!n"); } else { newNode = (struct node *)malloc(sizeof(struct node)); newNode->data = data; newNode->next = NULL; newNode->prev = last;
- 5. last->next = newNode; last = newNode; printf("NODE INSERTED SUCCESSFULLY AT THE END OF LISTn"); } } /** * Inserts a node at any position in the doubly linked list * @data Data of the new node to be inserted * @position Position where to insert the new node */ void insertAtN(int data, int position) { int i; struct node * newNode, *temp; if(head == NULL) { printf("Error, List is empty!n"); } else { temp = head; i=1; while(i<position-1 && temp!=NULL) { temp = temp->next; i++; } if(position == 1) { insertAtBeginning(data); } else if(temp == last) { insertAtEnd(data); } else if(temp!=NULL) { newNode = (struct node *)malloc(sizeof(struct node)); newNode->data = data; newNode->next = temp->next; // Connect new node with n+1th node newNode->prev = temp; // Connect new node with n-1th node if(temp->next != NULL) { /* Connect n+1th node with new node */ temp->next->prev = newNode; } /* Connect n-1th node with new node */ temp->next = newNode;
- 6. printf("NODE INSERTED SUCCESSFULLY AT %d POSITIONn", position); } else { printf("Error, Invalid positionn"); } } } Output